A non-political friend here commented on the fact that Trump sat while having Mamdani stand beside him. She doesn't like talking politics, still even saw that as extreme rudeness and arrogance on Trump's part.
I'm not sure that it was. Let's not forget that on a few occasions last year, Trump sat at his desk while his then-buddy Elon Musk stood at his side.
I think it's also possible that his ankles were badly swollen again, and he didn't want the press and cameras to catch that. So he didn't want to place the two of them in the yellow chairs.